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| author | Like Xu <likexu@tencent.com> | 2022-12-07 15:15:05 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-12-23 12:06:45 -0500 |
| commit | 55c590adfe18b5380f7c4ae3696468bc5c916ee5 (patch) | |
| tree | e9ea40a36c60cdd277d0b9015c590680912095d0 /arch | |
| parent | 549a715b98a13c6d05452be3ad37e980087bb081 (diff) | |
| download | lwn-55c590adfe18b5380f7c4ae3696468bc5c916ee5.tar.gz lwn-55c590adfe18b5380f7c4ae3696468bc5c916ee5.zip | |
KVM: x86/pmu: Prevent zero period event from being repeatedly released
The current vPMU can reuse the same pmc->perf_event for the same
hardware event via pmc_pause/resume_counter(), but this optimization
does not apply to a portion of the TSX events (e.g., "event=0x3c,in_tx=1,
in_tx_cp=1"), where event->attr.sample_period is legally zero at creation,
thus making the perf call to perf_event_period() meaningless (no need to
adjust sample period in this case), and instead causing such reusable
perf_events to be repeatedly released and created.
Avoid releasing zero sample_period events by checking is_sampling_event()
to follow the previously enable/disable optimization.
Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20221207071506.15733-2-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/pmu.c | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/pmu.h | 3 |
2 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 684393c22105..eb594620dd75 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -238,7 +238,8 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc) return false; /* recalibrate sample period and check if it's accepted by perf core */ - if (perf_event_period(pmc->perf_event, + if (is_sampling_event(pmc->perf_event) && + perf_event_period(pmc->perf_event, get_sample_period(pmc, pmc->counter))) return false; diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h index 85ff3c0588ba..cdb91009701d 100644 --- a/arch/x86/kvm/pmu.h +++ b/arch/x86/kvm/pmu.h @@ -140,7 +140,8 @@ static inline u64 get_sample_period(struct kvm_pmc *pmc, u64 counter_value) static inline void pmc_update_sample_period(struct kvm_pmc *pmc) { - if (!pmc->perf_event || pmc->is_paused) + if (!pmc->perf_event || pmc->is_paused || + !is_sampling_event(pmc->perf_event)) return; perf_event_period(pmc->perf_event, |